Low Track Pitch Write Module And Bidirectional Tape Head

ABSTRACT

A low track pitch write module and bidirectional tape head for writing and/or reading data on a magnetic recording tape. The write module and tape head have a tape bearing surface for engaging the magnetic recording tape and plural write elements. The write elements are arranged so that the write gaps of adjacent write elements are spaced from each other by not more than approximately one write gap width, while being generally aligned along an axis that is perpendicular to a direction of movement of the magnetic recording tape. The write elements may have a planar or vertical construction comprising plural thin film layers oriented in generally parallel or perpendicular relationship with the tape bearing surface. One or more read element arrays may also be provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to tape drive data storage systems. Moreparticularly, the invention is directed to thin film tape heads forreading and writing data on magnetic recording tape.

2. Description of the Prior Art

Thin film tape heads for magnetic information storage systems (e.g.,tape drives) have been constructed using the same fabrication techniquesused by disk drive manufacturers. A characteristic of such constructionis that the thin film layers which comprise the read and writetransducer elements are oriented perpendicularly to the tape bearingsurface (TBS) of the head. Such heads may be referred to as “vertical”heads due to the fact that the read and write gap portions are situatedat the TBS, while the element layer structures extend vertically awayfrom the TBS. In a vertical head with multitrack recording capability,plural transducer elements are commonly arranged side-by-side to form alinear transducer array that is transverse to the direction of tapemovement. Each transducer element in the array is positioned to write orread a separate longitudinal track on the tape. This arrangement isshown in FIG. 1, which depicts a vertical head “H” having an array ofthin film transducer elements “E” whose gaps “G” engage a tape “T” alongtracks “TR” in the direction of tape movement “D.” FIG. 2 illustrates anexemplary internal construction of the vertical head “H” in which thetransducers comprise alternating read and write elements “R” and “W.” Asshown in FIG. 3, the vertical head “H” of FIG. 2 can be secured to amounting block “MB” in association with a complimentary vertical head“H” whose read and write elements are in reverse order. The resultanthead assembly will have read/write element pairs that are aligned in thetrackwise direction of the tape “T.” This arrangement providesconventional read-after-write capability in which data written to thetape “T” is immediately read back and checked for errors.Read-after-write capability may also be achieved with a single verticalhead having pairs of trackwise-aligned read and write elements that areconstructed according to the well-known “piggyback” arrangement used indisk drives. Other conventional vertical head designs include heads inwhich all of the transducer elements “E” are either read elements orwrite elements. Read-after-write capability may then be achieved bybonding a read-only head to a write-only head to providetrackwise-aligned read and write element pairs.

A disadvantage of vertical head constructions as described above is thatthe transducer element gaps at the TBS must be sufficiently spaced fromeach other to provide room for the major portion of the transducerelement structure that is recessed behind the TBS. For a write element,the recessed structure includes the pole pieces and the coil windings,which (as can be seen in FIG. 2) are quite bulky as compared to thewrite gap structure at the TBS. For a read element, the recessedstructure includes the electrical leads and magnetic hard biasingelements (if present). These are also relatively bulky compared to theread gap structure at the TBS, although less so compared to writeelements. The foregoing spacing requirements render the transducer arrayof a vertical head much wider than it needs to be for the number oftracks being read or written at any given moment. The problem is thatthe gap pitch within the transducer array is much larger than the gapwidth, such that for every track being read or written by the array,there will be space between the tracks where no transducing occurs. This“comb” effect can be seen in FIG. 2, which shows that for every pair oftracks “TR” aligned with adjacent read and write elements “R” and “W,”there is inter-track white space on the tape “T” that is not tranduced.

The comb effect can be solved by stepping the head in a cross-trackdirection during multiple transducing passes, such that the inter-trackwhite space is ultimately recorded with data after some number of passeshave been made. Tape tracks can also be written at less than the gapwidth of the write transducers using a process known as “shingling.”According to this technique, the head is stepped by less than the writeelement gap width for each successive transducing pass, such that theedge of a previously written track is overwritten during the next pass,much like shingles on a roof.

Although the foregoing track writing techniques allow data to be denselypacked on a tape, a continuing unresolved problem is trackmisregistration caused by tape dimensional changes between writing andreading operations. For example, a tape may be written with data underone set of temperature and humidity conditions, and then later readfollowing exposure to different environmental conditions. Forconventional tape material, the dimensions can change by as much as0.12%. These tape dimensional changes will widen or narrow the tapetrack spacing geometry, resulting in track misregistration with the tapehead whose gap spacing geometry is substantially unchanged. Althoughrotation of the tape head can be used to address the misregistrationproblem by changing the effective track pitch of the transducer array,this solution requires sophisticated mechanics and skew compensationcircuitry.

To illustrate the misregistration problem, assume the transducer arrayspans×μm between the outermost elements, and the percentage change intape dimension is 0.12%. The resultant change in the spacing of the tapetracks under the outermost elements will be 0.0012×μm. On the otherhand, if the transducer array spans 0.5×μm, then a 0.12% change in tapedimension will only change the tape track spacing under the outermostelements by 0.0006×μm. The 0.5× transducer array span will thusexperience only half of the tape dimensional change that is experiencedby the ×transducer span, such that track misregistration is less likely.Note that if the head gap pitch can be reduced to a value whichapproaches the gap width, a further advantage of being able to performcontiguous-track bundle writing could be achieved. The head would thenbe able to read and write the entire tape area underlying the transducerarray in a single pass, thereby alleviating the precise trackingrequired for shingling tracks in multiple passes.

Accordingly, it is desired to have an improved design for a thin filmtape head for reading and writing data on magnetic recording tape. Whatis particularly needed is a head design that provides the ability toreduce the gap pitch of read and write elements, especially to levelsapproaching the gap width.

SUMMARY OF THE INVENTION

The foregoing problems are solved and an advance in the art is obtainedby a low track pitch write module and bidirectional tape head forwriting and optionally reading data on a magnetic recording tape. Thewrite module and tape head have a tape bearing surface for engaging themagnetic recording tape and plural write elements. Each of the writeelements comprises first and second pole pieces having respective poletips that are spaced from each other at the tape bearing surface to forma write gap. The write elements further include back gap regions wherethe poles pieces are magnetically connected to each other. The writeelements are arranged so that the write gaps of adjacent write elementsare spaced from each other by not more than approximately one gap width,while being generally aligned along an axis that is perpendicular to adirection of movement of the magnetic recording tape.

According to one exemplary embodiment, write elements in the writemodule each comprise plural thin film layers oriented in generallyparallel planar relationship with the write module tape bearing surface.The write elements may comprise a pancake coil construction or a helicalcoil construction. In both cases, the write elements may comprise a pairof pole tips providing a write gap at the write module tape bearingsurface and a pair of pole pieces extending from the pole tips to a backgap region where the pole pieces are joined, with the back gap regionbeing spaced in a trackwise direction from the write gap. The writeelements may be arranged so that adjacent write elements have adjacentpole tips but oppositely extending pole pieces and back gaps. Thisallows the write elements to be arranged with spaced write gaps or withnear contiguous write gaps in order to bundle write contiguous tracks onthe magnetic recording medium.

According to another embodiment, the write elements have a verticalconstruction comprising plural thin film layers oriented in generallyperpendicular relationship with the tape bearing surface. The writeelements may be constructed with a helical coil configuration in which ahelical coil wraps around one of the vertical pole pieces. To facilitatenear contiguous spacing of the write gaps, portions of adjacent writeelements may be arranged in alternating layers.

Read-after-write capability may be provided by mounting one or moreseparate read modules in a fixed relationship relative to a write modulethat comprises the write elements. If vertical write elements are used,one or more read element arrays having a vertical construction may befabricated on a common substrate with the write elements. Adjacent readelements may be disposed in alternating vertical layers to reduce readgap spacing requirements.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following more particular description of exemplaryembodiments of the invention, as illustrated in the accompanyingDrawings, in which:

FIG. 1 is a perspective view showing a prior art thin film vertical tapehead;

FIG. 2 is a perspective view showing an exemplary construction of theprior art tape head of FIG. 1;

FIG. 3 is a side elevation view showing a pair of the vertical tapeheads of FIG. 1 secured to a mounting block;

FIG. 4 is a partial plan view showing a tape bearing surface of anexemplary hybrid tape head, with a segment of magnetic recording tapesuperimposed over the tape head;

FIG. 5 is an enlarged plan view showing a portion of a write module ofthe tape head of FIG. 4;

FIG. 6 is write element cross-sectional view taken along line 6-6 inFIG. 5;

FIG. 7 is a head cross-sectional view taken along line 7-7 in FIG. 4;

FIG. 8 is a plan view showing a write module servo reader;

FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 8;

FIG. 10 is a side view taken in the direction of the arrows 10-10 inFIG. 9;

FIG. 11 is a partial plan view showing a tape bearing surface of anotherexemplary tape head, with a segment of magnetic recording tapesuperimposed over the tape head;

FIG. 12 is an enlarged plan view showing a portion of a write module ofthe tape head of FIG. 11;

FIG. 12A is an enlarged plan view showing a modified arrangement ofwrite elements of the write module shown in FIG. 12;

FIG. 13 is write element cross-sectional view taken along line 13-13 inFIG. 12;

FIG. 14 is a head cross-sectional view taken along line 14-14 in FIG.11;

FIG. 15 is a partial plan view showing a tape bearing surface of anotherexemplary tape head, with a segment of magnetic recording tapesuperimposed over the tape head;

FIG. 16 is an enlarged partial cross-sectional view taken along line16-16 in FIG. 15 and showing a portion of a write module of the tapehead of FIG. 15;

FIG. 16A is a write element cross-sectional view taken along line16A-16A in FIG. 16;

FIG. 17 is write element cross-sectional view taken along line 17-17 inFIG. 16;

FIG. 18 is a head cross-sectional view taken along line 18-18 in FIG.15;

FIG. 19 is a partial plan view showing a tape bearing surface of anotherexemplary tape head, with a segment of magnetic recording tapesuperimposed over the tape head;

FIG. 20 is a head cross-sectional view taken along line 20-20 in FIG.19;

FIG. 21 is a partial plan view showing a tape bearing surface of a tapehead constructed in accordance with another exemplary embodiment of thepresent invention, with a segment of magnetic recording tapesuperimposed over the tape head;

FIG. 22 is a head cross-sectional view taken along line 22-22 in FIG.21;

FIG. 23 is a functional block diagram showing a tape drive data storagedevice; and

FIG. 24 is a perspective view showing an exemplary construction of thetape drive storage device of FIG. 20 for use with cartridge-based tapemedia.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The invention will now be described by way of exemplary embodimentsshown by the drawing figures (which are not necessarily to scale), inwhich like reference numerals indicate like elements in all of theseveral views.

Turning now to FIG. 4, a tape head 2 includes a planar write module 4that may be used alone or optionally arranged with one or both of a pairof vertical read modules 6 and 8. The write module 4 has a write moduletape bearing surface 10 for engaging a magnetic recording tape “T,” oneedge of which is shown in FIG. 4. As additionally shown in FIGS. 5-7,the write module 4 has a planar head construction in which plural writeelements 12 in the write module 4 each comprise plural thin film layers“L” oriented in generally parallel planar relationship with the writemodule tape bearing surface 10. It will be seen that the write elements12 are arranged so that the transducing gaps (write gaps) 14 of adjacentwrite elements are generally aligned along an axis “A-A” that isperpendicular to a streaming direction of the magnetic recording tape(shown by the arrow “D” in FIG. 4).

Each of the optional read modules 6 and 8 has a read module tape bearingsurface 16 for engaging the magnetic recording tape “T.” As additionallyshown in FIG. 7, the read modules 6 and 8 have a conventional verticalhead construction in which plural read elements 18 each comprise pluralthin film layers oriented in generally perpendicular relationship withthe read module tape bearing surface 16. Although not shown, adjacentread elements 18 may be formed in different layers of the read modules 6and 8 to reduce read gap spacing requirements. Although the read modules6 and 8 are shown in FIGS. 4 and 7 as being contiguous with the writemodule 4, one or both of the read modules could be spaced from the writemodule in a fixed relationship therewith.

In the exemplary embodiment represented by FIGS. 4-7, the write elements12 comprise a pancake coil construction. According to this construction,the write coil 20 is constructed with plural coil windings in a singleone of the thin film layers “L,” as can be seen in FIG. 6. A pair ofcontact pads 22 and 24 are provided for connecting the write coil 20 toan information-modulated current source (not shown). The write elements12 further comprise a pair of pole tips 26 and 28 that provide the writegap 14 at the write module tape bearing surface 10. A pair of polepieces 30 and 32 respectively extend from the pole tips 26 and 28 to aback gap region 34 where the pole pieces are joined. The pole tips 26/28and the pole pieces 30 and 32 can be formed from any suitablemagnetically permeable material of the type conventionally used tofabricate inductive write heads for information storage. As can be seenin FIG. 6, the pole pieces 30 and 32 initially extend from the pole tips26 and 28 in a direction that is generally perpendicular to the writemodule tape bearing surface 10. Each pole piece 30 and 32 then makes anapproximate 90° bend at a separate one of the layers “L” of the writemodule 4, and thereafter extends generally parallel to the write moduletape bearing surface 10 to the back gap region 34. The back gap region34 is thereby spaced in a trackwise (i.e., along the track) directionfrom the write gap 14.

It will be seen in FIGS. 5 and 6 that the write coil 20 wraps around theback gap region 34 with the coil windings on one side of the back gapregion being disposed between the pole pieces 30 and 33. When the writecoil 20 is energized, it will induce magnetic flux in the pole pieces 30and 32 so as to produce a magnetic field at the pole tips 26 and 28 thatpropagates across the write gap 14. It will be appreciated that thestrength of the magnetic field at the write gap 14 depends in part onthe number of windings of the write coil 20. Although not shown, one wayto increase the number of coil windings without increasing the overallsize of the write elements (when viewed in the plan view orientation ofFIG. 5) would be to form the additional windings on one or more separatelayers “L” of the write module 4.

As additionally shown in FIGS. 5 and 6, the write elements 12 arearranged so that adjacent write elements have adjacent pole tips 26/28but oppositely extending pole pieces 30/32 and back gaps 34. Dependingon the size of the write coil 20, the write elements 12 may be arrangedwith spaced write gaps (as shown in FIG. 5) that are spaced by a desiredseparation distance (preferably not more than approximately one gapwidth), or with near contiguous write gaps (not shown) having a nominalspacing that is substantially less than one gap width in order to bundlewrite on contiguous tracks of the magnetic recording medium. In thefirst instance, the gap pitch (i.e., the distance between thecenterlines of adjacent write gaps) will be approximately 2 gap widths.In the second instance, the gap pitch will approximate the gap width. Byway of example, a gap separation corresponding to the width of the writeelement erase band could be used. The gap pitch in that case will be thesum of the gap width and the erase band width. Typically, the erase bandwidth is approximately 3-5 times the gap size (i.e., the separationbetween the pole pieces 30/32 in the direction of tape movement).Assuming a typical gap size of approximately 5 microns, the gap spacing(if equal to the erase band width), would be approximately 15-25microns. Note that the size of the write coil 20 will depend in largepart on the number of coil windings formed in any given layer “L” of thewrite module 4, which can be controlled by using plural layers asdiscussed above.

As shown in FIG. 4, the tape head 2 includes servo read elements forreading conventional timing-based servo tracks “ST” on the tape “T.” Theservo read elements may be provided by additional read elements 18 onthe read modules 6 and 8, or they may be provided by planar servo readelements 36 on the write module 4. As shown in FIGS. 8-10, each planarservo read element 36 comprises a sensor structure 38 formed in pluralthin film layers “L” of the write module 4 that are oriented in parallelplanar relationship with the write module tape bearing surface 10. Aspersons skilled in the art will appreciate, the sensor structure layersmay include a magnetic pinned layer 40, a spacer layer 42 and a magneticfree layer 44. A pair of electrode/hard biasing structures 46 may beprovided on each side of the sensor structure to provide a CIP(Current-In-Plane) sensor. Although not shown, a CPP(Current-Perpendicular to-Plane) sensor could also be used. Aconventional flux guide is used to carry magnetic flux from the writemodule tape bearing surface 10 to the free layer 44.

FIG. 7 shows the tape head 2 when viewed from the edge of the tape “T”of FIG. 4. As can be seen, electrical connections are made to the writeelements 12 from electrical contact pads 48 formed on the surface of thetape head 2 which is opposite from the tape bearing surface 10.Electrical cables (not shown) may be attached to the contact pads 48using conventional techniques. Electrical connections to the readerelements 18 can be provided using conventional contact pads of the typeshown in FIG. 1, as are commonly used for vertical read elements.Although not shown, it would be possible to fabricate driver components,such as FETs (Field Effect Transistors), above the contact pads 48 ofthe write module 4. Alternatively, the drivers may be fabricated onseparate chips, which are then mounted close to the tape head 2. Thetape bearing surfaces 10 and 16 of the tape head 2 may be lapped todefine a preferred tape wrap angle as the tape “T” streams over thehead.

Turning now to FIGS. 11-14, an alternative write module 4′ is shown foruse in the tape head 2 in which the write elements 12′ comprise ahelical coil construction. According to this construction, the writecoil 20′ is constructed with plural coil windings in plural film layers“L,” as can be seen in FIG. 13. In particular, a first set of coilwinding elements 20A′ is formed in a first one of the layers “L,” asecond set of coil winding elements 20B′ is formed in a second one ofthe layers “L,” and third and fourth sets of coil winding elements 20C′and 20D′ (see FIG. 12) are formed in the intermediate layers that liebetween the coil winding elements 20A′ and 20B′. A pair of contact pads22′ and 24′ are provided for connecting the write coil 20′ to aninformation-modulated current source (not shown). The write elements 12′further comprise a pair of pole tips 26′ and 28′ that provide the writegap 14′ at the write module tape bearing surface 10′. A pair of polepieces 30′ and 32′ respectively extend from the pole tips 26′ and 28′ toa back gap region 34′ where the pole pieces are joined. The pole tips26′/28′ and the pole pieces 30′ and 32′ can be formed from any suitablemagnetically permeable material of the type conventionally used tofabricate inductive write heads for information storage. As can be seenin FIG. 13, the pole pieces 30′ and 32′ initially extend from the poletips 26′ and 28′ in a direction that is generally perpendicular to thewrite module tape bearing surface 10′. Each pole piece 30′ and 32′ thenmakes an approximate 90° bend at a separate one of the layers “L” of thewrite module 4′, and thereafter extends generally parallel to the writemodule tape bearing surface 10′ to the back gap region 34′. The back gapregion 34′ is thereby spaced in a trackwise direction from the write gap14′.

It will be seen in FIG. 13 that the write coil 20′ wraps around the polepiece 32′. When the write coil 20′ is energized, it will induce magneticflux in the pole pieces 30′ and 32′ so as to produce a magnetic field atthe pole tips 26′ and 28′ that propagates across the write gap 14′. Itwill be appreciated that the strength of the magnetic field at the writegap 14′ depends in part on the number of windings of the write coil 20′.The number of winding of the write coil 20′ can be increased byincreasing the length of the pole pieces 30′ and 32′.

As best shown in FIGS. 11 and 12, the write elements 12′ are arranged sothat adjacent write elements have adjacent pole tips 26′/28′ butoppositely extending pole pieces 30′/32′ and back gaps 34′. It will alsobe seen that the write elements 12′ are arranged so that the write gaps14′ of adjacent write elements are generally aligned along an axis “A-A”that is perpendicular to a streaming direction of the magnetic recordingtape (shown by the arrow “D” in FIG. 11). For processing expediency, itmay be desirable to slightly stagger the transducing gaps 14′ ofadjacent write elements 12′, as shown in FIG. 12A. However, the writegaps 14′ nonetheless remain symmetrically aligned about each side of thecommon axis “A-A” that is perpendicular to the direction of tapemovement. Depending on the size of the write coil 20′, the writeelements 12′ may be arranged with spaced write gaps (not shown) that arespaced by approximately one gap width (i.e., a gap pitch of twice thegap width), or with near contiguous transducing gaps (as shown in FIGS.11 and 12) having a nominal spacing that is substantially less than onegap width in order to bundle write on contiguous tracks of the magneticrecording medium. As described above in connection with the writeelements 12 of FIGS. 4-7, a gap spacing corresponding to the erase bandwidth of the write elements 12′ may be used. The gappitch will then bethe sum of the gap width and the erase band width. Assuming a typicalgap size of approximately 5 microns, the gap spacing (if equal to theerase band width), would be approximately 15-25 microns (assuming atypical erase band width of approximately 3-5 times the gap size). Notethat the helical configuration of the write coil 20′ allows the writeelements 12′ to have a relatively narrow footprint (as compared to thepancake coil configuration described above) that facilitates the nearcontiguous gap configuration.

Turning now to FIG. 15, an alternative tape head 102 is constructedaccording to an exemplary three-module configuration in which a writemodule 104 may be used alone or optionally arranged with one or both ofa pair of read modules 106 and 108. The write module 104 has a writemodule tape bearing surface 110 for engaging a magnetic recording tape“T,” one edge of which is shown in FIG. 15. As additionally shown inFIGS. 16-18, the write module 104 has a vertical head construction inwhich plural write elements 112 in the write module 104 each compriseplural thin film layers “L” oriented in generally perpendicularrelationship with the write module tape bearing surface 110. It will beseen in FIG. 16A that the write elements 112 are arranged so that thetransducing gaps 114 of adjacent write elements are generally alignedalong an axis A-A that is perpendicular to a streaming direction of themagnetic recording tape (shown by the arrow “D”).

Each of the optional read modules 106 and 108 has a read module tapebearing surface 116 for engaging the magnetic recording tape “T.” Asadditionally shown in FIG. 18, the read modules 106 and 108 have aconventional vertical head construction in which the read elements 118each comprise plural thin film layers oriented in generallyperpendicular relationship with the read module tape bearing surface116. Although not shown, adjacent read elements 118 may be formed indifferent layers of the read modules 106 and 108 to reduce read gapspacing requirements. Although the read modules 106 and 108 are shown inFIG. 15 as being contiguous with the write module 104, one or both ofthe read modules could be spaced from the write module in a fixedrelationship therewith.

As can be seen in FIGS. 16 and 17, the write elements 112 comprise ahelical coil construction. According to this construction, the writecoil 120 is constructed with plural coil windings in plural film layers“L” as can be seen in FIG. 17. In particular, a first set of coilwinding elements 120A is formed in a first one of the layers “L,” asecond set of coil winding elements 120B is formed in a second one ofthe layers “L” and third and fourth sets of coil winding elements 120Cand 120D (see FIG. 16) are formed in the intermediate layers that liebetween the coil winding elements 120A and 120B. A pair of contact pads122 and 124 are provided for connecting the write coil 120 to aninformation-modulated current source (not shown). The write elements 112further comprise a pair of pole tips 126 and 128 that provide the writegap 114 at the write module tape bearing surface 110. A pair of polepieces 130 and 132 respectively extend from the pole tips 126 and 128 toa back gap region 134 where the pole pieces are joined. The pole tips126/128 and the pole pieces 130 and 132 can be formed from any suitablemagnetically permeable material of the type conventionally used tofabricate inductive write heads for information storage. As can be seenin FIG. 17, the pole pieces 130 and 132 respectively extend from thepole tips 126 and 128 in a direction that is generally perpendicular tothe write module tape bearing surface 110 to the back gap region 134.

It will be seen in FIG. 17 that the write coil 120 wraps around the polepiece 132. When the write coil 120 is energized, it will induce magneticflux in the pole pieces 130 and 132 so as to produce a magnetic field atthe pole tips 126 and 128 that propagates across the write gap 114. Itwill be appreciated that the strength of the magnetic field at the writegap 114 depends in part on the number of windings of the write coil 120.The number of winding of the write coil 120 can be increased byincreasing the length of the pole pieces 130 and 132.

As additionally shown in FIGS. 16A and 17, the write elements 112 arearranged so that adjacent write elements have adjacent pole tips 114 andwith the pole pieces 130 formed in a common one of the layers “L.” Thepole pieces 132 and the back gaps 134 are formed in alternating layers“L” of the write module 104 to reduce write gap spacing requirements. Avariant of this construction would be to form the write elements 112 sothat the pole tips 114 of adjacent elements are formed in the samelayers “L.” This would result in the write gaps of the pole tips 114being centered on the axis “A” in FIG. 16A. The write elements 112 maythus be arranged with near contiguous write gaps (see FIGS. 16 and 16A)in order to bundle write on contiguous tracks of the magnetic recordingmedium. For example, a gap spacing corresponding to the erase band widthof the write elements 112 may be used. The gap pitch will then be thesum of the gap width and the erase band width. Assuming a typical gapsize of approximately 5 microns, the gap spacing (if equal to the eraseband width), would be approximately 15-25 microns (assuming a typicalerase band width of approximately 3-5 times the gap size). As shown inFIG. 16A, the write elements 112 are arranged so that the write gaps 114of adjacent write elements are generally aligned along an axis “A-A”that is perpendicular to a streaming direction of the magnetic recordingtape (shown by the arrow “D”).

As shown in FIG. 15, the tape head 102 includes servo read elements forreading conventional timing-based servo tracks “ST” on the tape “T.” Theservo read elements may be provided by additional read elements 118 onthe read modules 16 and 18 (assuming the read modules are present), orthey may be provided by servo read elements 36 on the write module 4.

FIG. 18 shows the tape head 102 when viewed from the edge of the tape“T” of FIG. 15. As can be seen, electrical connections are made to thewrite elements 114 from electrical contact pads 148 formed on thesurface of the tape head 102 which is opposite from the tape bearingsurface 110. Electrical cables (not shown) may be attached to thecontact pads 148 using conventional techniques. Electrical connectionsto the reader elements 118 can be provided using conventional contactpads of the type shown in FIG. 1, as are commonly used for vertical readelements. Although not shown, it would be possible to fabricate drivercomponents, such as FETs (Field Effect Transistors), above the contactpads 148 of the write and read modules 14, 16 and 18. Alternatively, thedrivers may be fabricated on separate chips, which are then mountedclose to the tape head 12. As further shown in FIG. 18, the tape bearingsurfaces 110 and 116 of the tape head 102 may be lapped to define apreferred tape wrap angle as the tape “T” streams over the head.

Turning now to FIGS. 19 and 20, a modified tape head 102′ is shown thatis identical in all respects to the tape head 102 with the exceptionthat the read module 108 is eliminated. Instead, there is only one readmodule 106 containing a first array of read elements 118, and a writemodule 110′ having an array of vertical write elements 112′ and anintegrated array of vertical read elements 118′. Although not shown, anEMI shielding layer is preferably formed in the write module 110′between the write element array and the read element array in order toprevent cross-talk between the write elements 112′ and the read elements118′.

Turning now to FIGS. 21 and 22, a second modified tape head 102″ isshown that is identical in all respects to the tape head 102 with theexception that the read modules 106 and 108 are eliminated. Instead, awrite module 110″ has a two integrated arrays of vertical read elements118″ that sandwich the array of vertical write elements 112″. Althoughnot shown, EMI shielding layers are preferably formed in the writemodule 110″ between the write elements array and the read element arraysin order to prevent cross-talk between the write elements 112″ and theread elements 118″.

Turning to FIG. 23, the inventive concepts herein described may beembodied in a tape drive data storage device (tape drive) 200 forstoring and retrieving data by a host data processing device 202, whichcould be a general purpose computer of other processing apparatusadapted for data exchange with the tape drive 200. The tape drive 200includes plural components providing a control and data transfer systemfor reading and writing host data on a magnetic tape medium. By way ofexample only, those components may conventionally include a channeladapter 204, a microprocessor controller 206, a data buffer 208, aread/write data flow circuit 210, a motion control system 212, and atape interface system 214 that includes a motor driver circuit 216 and aread/write head unit 218.

The microprocessor controller 206 provides overhead controlfunctionality for the operations of the tape drive 200. As isconventional, the functions performed by the microprocessor controller206 are programmable via microcode routines (not shown) according todesired tape drive operational characteristics. During data writeoperations (with all dataflow being reversed for data read operations),the microprocessor controller 206 activates the channel adapter 204 toperform the required host interface protocol for receiving aninformation data block. The channel adapter 204 communicates the datablock to the data buffer 208 that stores the data for subsequentread/write processing. The data buffer 208 in turn communicates the datablock received from the channel adapter 204 to the read/write dataflowcircuitry 210, which formats the device data into physically formatteddata that may be recorded on a magnetic tape medium. The read/writedataflow circuitry 210 is responsible for executing read/write datatransfer operations under the control of the microprocessor controller206. Formatted physical data from the read/write data flow circuitry 210is communicated to the tape interface system 214. The latter includesone or more read/write heads in the read/write head unit 218, and drivemotor components (not shown) for performing forward and reverse movementof a tape medium 220 mounted on a supply reel 222 and a take-up reel224. The drive components of the tape interface system 214 arecontrolled by the motion control system 212 and the motor driver circuit216 to execute such tape movements as forward and reverse recording andplayback, rewind and other tape motion functions. In addition, inmulti-track tape drive systems, the motion control system 212transversely positions the read/write heads relative to the direction oflongitudinal tape movement in order to record data in a plurality oftracks.

In most cases, as shown in FIG. 24, the tape medium 220 will be mountedin a cartridge 226 that is inserted in the tape drive 200 via a slot228. The tape cartridge 226 comprises a housing 230 containing themagnetic tape 220. The supply reel 222 is shown to be mounted in thehousing 230.

Accordingly, a low track pitch write head and bidirectional tape headfor writing and/or reading data on a magnetic recording tape has beendisclosed. While various embodiments of the invention have been shownand described, it should be apparent that many variations andalternative embodiments could be implemented in accordance with theteachings herein. It is understood, therefore, that the invention is notto be in any way limited except in accordance with the spirit of theappended claims and their equivalents.

1. A write module for writing data on a magnetic recording tape,comprising: a tape bearing surface for engaging said magnetic recordingtape; plural write elements, each of which comprises: a first polepiece; a second pole piece; said first and second pole pieces havingrespective pole tips separated from each other at said tape bearingsurface to form a write gap having a write gap length that represents aseparation distance between said respective pole tips, and said poletips also having a width dimension defining a write gap width; saidfirst and second pole pieces further having respective back gap regionsthat are magnetically connected to each other; said write elements beingconstructed and arranged so that the write gaps of adjacent writeelements are spaced from each other by not more than approximately onewrite gap width; said write gaps being generally aligned along an axisthat is perpendicular to a direction of movement of said magneticrecording tape; and wherein said write elements having a verticalconstruction comprising plural thin film layers oriented in generallyperpendicular relationship with said tape bearing surface, with portionsof adjacent write elements being arranged in alternating thin filmlayers to facilitate reduced write gap spacing. 2-4. (canceled)
 5. Awrite module in accordance with claim 1 wherein said write elementscomprise a helical construction in which a helical coil wraps around oneof said pole pieces.
 6. A write module in accordance with claim 1 incombination with one or more read modules each comprising an array ofread elements, said read module(s) being mounted in a fixed relationshiprelative to said write module.
 7. A write module in accordance withclaim 1 in combination with one or more arrays of read elements formedon a common substrate with said write elements.
 8. A write module inaccordance with claim 7 wherein said read elements in said read elementarray(s) have a vertical construction comprising plural thin film layersoriented in generally perpendicular relationship with said tape bearingsurface.
 9. In a tape drive, a tape head for writing data on a magneticrecording tape, comprising: a substrate; a tape bearing surface forengaging said magnetic recording tape; plural write elements formed onsaid substrate, each of which comprises: a first pole piece; a secondpole piece; said first and second pole pieces having respective poletips separated from each other at said tape bearing surface to form awrite gap having a write gap length that represents a separationdistance between said respective pole tips, and said pole tips alsohaving a width dimension defining a write gap width; said first andsecond pole pieces further having respective back gap regions that aremagnetically connected to each other; said write elements beingconstructed and arranged so that the write gaps of adjacent writeelements are in a near contiguous relationship in which said write gapsare spaced from each other by not more than approximately 3-5 times saidgap length to facilitate contiguous track bundle writing; said writegaps being generally aligned along an axis that is perpendicular to adirection of movement of said magnetic recording tape; and said writeelements having a vertical construction comprising plural thin filmlayers oriented in generally perpendicular relationship with said tapebearing surface.
 10. A tape drive in accordance with claim 9 whereinportions of adjacent write elements are arranged in alternating thinfilm layers to facilitate reduced write gap spacing.
 11. A tape drive inaccordance with claim 9 wherein said write elements comprise a helicalconstruction in which a helical coil wraps around one of said polepieces.
 12. A tape drive in accordance with claim 9 wherein there areone or more arrays of read elements formed on said substrate.
 13. A tapedrive in accordance with claim 12 wherein read elements in said readelement array(s) have a vertical construction comprising plural thinfilm layers oriented in generally perpendicular relationship with saidtape bearing surface.
 14. A tape drive in accordance with claim 13wherein adjacent read elements are arranged with read gaps having a readgap spacing equal to said spacing between said write gaps.
 15. A tapedrive in accordance with claim 14 wherein adjacent read elements areformed in alternating thin film layers to facilitate reduced read gapspacing. 16-20. (canceled)
 21. In a tape drive, a tape head for writingdata on a magnetic recording tape, comprising: a substrate; a tapebearing surface for engaging said magnetic recording tape; plural writeelements formed on said substrate, each of which comprises: a first polepiece; a second pole piece; said first and second pole pieces havingrespective pole tips separated from each other at said tape bearingsurface to form a write gap having a write gap length that represents aseparation distance between said respective pole tips, and said poletips also having a width dimension defining a write gap width; saidfirst and second pole pieces further having respective back gap regionsthat are magnetically connected to each other; said write elements beingconstructed and arranged so that the write gaps of adjacent writeelements are spaced from each other by not more than approximately onewrite gap width; said write gaps being generally aligned along an axisthat is perpendicular to a direction of movement of said magneticrecording tape; and said write elements having a vertical constructioncomprising plural thin film layers oriented in generally perpendicularrelationship with said tape bearing surface.
 22. A tape drive inaccordance with claim 21 wherein portions of adjacent write elements arearranged in alternating thin film layers to facilitate reduced write gapspacing.
 23. A tape drive in accordance with claim 21 wherein said writeelements comprise a helical construction in which a helical coil wrapsaround one of said pole pieces.
 24. A tape drive in accordance withclaim 21 wherein there are one or more arrays of read elements formed onsaid substrate.
 25. A tape drive in accordance with claim 24 whereinread elements in said read element array(s) have a vertical constructioncomprising plural thin film layers oriented in generally perpendicularrelationship with said tape bearing surface.
 26. A tape drive inaccordance with claim 24 wherein adjacent read elements are arrangedwith read gaps having a read gap spacing equal to said spacing betweensaid write gaps.
 27. A tape drive in accordance with claim 24 whereinadjacent read elements are formed in alternating thin film layers tofacilitate reduced read gap spacing.
 28. A tape drive in accordance withclaim 21 wherein said substrate is part of a write module and said tapehead further includes one or more read modules each comprising an arrayof read elements, said read module(s) being mounted in a fixedrelationship relative to said write module.